The present invention relates to an operating-element arrangement for controlling the longitudinal movement of a motor vehicle, and more particularly, to an arrangement with a user-actuatable operating element which, when actuated in a first actuation direction, brings about an increase in and, when actuated in a second actuation direction opposite to the first, brings about a reduction in the longitudinal movement of the vehicle. The actuating force exerted on the operating element determines the change in longitudinal movement to be brought about, and the position of rest of the operating element is displaced in dependence on the longitudinal movement of the vehicle.
In known operating-element arrangements, one user-actuatable operating element, preferably a manually operable control stick, serves both for the positive acceleration and for the deceleration of the vehicle, thereby dispensing with conventional accelerator and brake pedal equipment.
One such known operating-element arrangement is described in H. Bubb, "Arbeitsplatz Fahrer--Eine ergonomische Studie" translation, "The Driver's Work Station--An Ergonomic Study"!, Automobil-Industrie translation, Automobile Industry! 3/95, page 265. In this known arrangement, the transverse dynamics are controlled by rotating two plate-like handles of the operating element which are connected mechanically to one another. The longitudinal dynamics are controlled by displacing the operating element which is guided movably via a yoke in a center console. Pushing the operating element forwards causes an increase in the vehicle longitudinal speed, with the acceleration to be attained being determined by the magnitude of the operating force directed forwards. Similarly, deceleration by way of a braking operation is determined by the operating force with which the operating element is pulled backwards. The respective vehicle speed is measured, and the operating element is displaced into a speed-proportional position by a suitable servodrive.
DE 44 04 594 A1 discloses a control stick for the acceleration and/or braking and for the steering of a motor vehicle. To control the vehicle, the control stick can be pivoted through two degrees of freedom of rotation, the axes of which are perpendicular to the longitudinal axis of the control stick and form an angle of 90.degree. with one another. The frictional or restoring forces of the control stick with respect to the degree of freedom of adjustment assigned to the steering can be increased as the driving speed increases.
U.S. Pat. No. 3,022,850 discloses an operating-element arrangement which contains a control stick for controlling both the transverse and the longitudinal dynamics of a motor vehicle. A longitudinal acceleration of the vehicle is requested by pivoting the rotatably mounted control stick forwards out of its essentially vertical rest position, which remains invariable, and a deceleration of the vehicle is correspondingly requested by pulling the control stick backwards.
An object of the present invention is to provide an operating-element arrangement which enables the vehicle driver to have comparatively comfortable control of the longitudinal movement of the vehicle.
This problem has been solved by providing an operating-element arrangement for controlling the longitudinal movement of a motor vehicle in which the operating element can be actuated by the actuating force exerted, counter to the effect of a reaction force exerted on the operating element, into a deflection position corresponding to the desired speed of the vehicle, the reaction force decreasing in dependence on the difference between the desired and the actual speed of the vehicle as the difference diminishes. Alternatively, the arrangement can have the operating element is arranged in such a way that it does not move relative to the vehicle body as a result of the actuating force exerted.
In these arrangements according to the present invention, the actuating force exerted on the user-actuatable operating element determines the change in the longitudinal vehicle movement requested in each case, for example the longitudinal vehicle speed or the longitudinal vehicle acceleration. The vehicle, in turn, complies by way of a corresponding accelerating or braking operation.
In the first-mentioned arrangement according to the present invention, the rest position of the operating element is displaced in dependence on the longitudinal vehicle movement, preferably parallel to the operating-element actuating force exerted and, in particular, parallel to the longitudinal direction of the vehicle. By virtue of this configuration, the vehicle driver receives an acknowledgement of longitudinal movement from the respective position of rest of the operating element. That is, based upon the displacement of the rest position of the operating element, the driver receives perceptible and/or visible information on the desired and/or actual vehicle speed (or acceleration).
The operating element can be deflected by the actuating force exerted in each case. A specific desired speed is assigned in each case to the deflection position assumed in which case the arrangement exerts on the operating element a reaction force which counteracts the actuating force exerted and which is reduced to zero as the difference between the desired and the actual speed of the vehicle decreases.
Consequently, the user receives acknowledgement, by way of force, of the respective instantaneous deviation of the actual speed from the desired speed and therefore of the vehicle acceleration or deceleration to be set. In other words, the vehicle driver will actuate the operating element with the greater force with a greater difference between the new desired speed and the previous or actual speed. As soon as the actual speed has reached the desired speed, the reaction force on the operating element preferably returns to zero, and the new force-free position of rest of the operating element represents the desired longitudinal vehicle speed which has been reached. Alternatively, for even more intuitive acknowledgement, a permanent reaction force which is greater than zero can be assigned to the state of a diminishing speed control difference.
According to another aspect of the present invention, adjustment of the rest position of the operating element takes place in dependence on the respective actual speed of the vehicle. As long as the vehicle driver actuates the operating element, the driver thus senses the displacement of the rest position of the operating element. By, for example, engagement of the driver's hand around the operating element, the driver perceives how the actual speed approaches the desired speed as a result of the vehicle acceleration or deceleration.
The second-mentioned arrangement according to the present invention is one with an isometric operating element. The magnitude of the actuating force serves directly as a measure of the change in the vehicle longitudinal movement. The operating element does not move relative to the vehicle body as a result of the actuating force exerted, but remains held in a fixed position.